Monomer and polymer adhesives/sealants are used in both industrial (including household) and medical/surgical applications. Included among these adhesives or sealants are cyanoacrylate monomers and polymers resulting therefrom. Since the discovery of the adhesive/sealant properties of such monomers and polymers, they have found wide use due to the speed with which they cure, the strength of the resulting bond formed, and their relative ease of use. These characteristics have made cyanoacrylate compositions the primary choice for numerous adhesive applications such as bonding plastics, rubbers, glass, metals, wood, and, more recently, medical, biological or living tissues.
Medical and surgical applications of cyanoacrylate compositions include their use as alternates or adjuncts to surgical sutures, meshes and staples or other medical devices in wound closure, as well as for covering and protecting surface wounds such as lacerations, abrasions, burns, stomatitises (plural of stomatitis), sores, and other surface wounds. When a cyanoacrylate composition is applied, it is usually applied in its monomeric form, and the resultant polymer creates the desired adhesive bond or sealant strength.
During the cyanoacrylate adhesive polymerization process, an exothermic reaction occurs that increases the temperature of the composition. Depending on the monomer utilized in the composition and the additives used, the temperature increase varies. In particular, as the viscosity of the adhesive increases, the ability to apply a thicker layer of material in a single application is present. This application creates the potential for a higher exotherm than if applying a less viscous composition using multiple layers to create an application of the same thickness. In addition, for some applications, is desirable to use a more viscous adhesive in order to prevent the adhesive from running when applied to a surface and spreading into a wound or along a surface to an area that does not require adhesive.
The increase in temperature of the adhesive composition due to exothermic polymerization of the monomeric component may be as low as 5° C. and as high as 70° C., depending on the composition of the adhesive. A temperature increase of as little as 45° C. of the adhesive composition placed on the surface of living tissue will generally cause discomfort. It is widely believed that temperatures above 60° C. generally cause tissue damage.
As disclosed in U.S. Pat. No. 6,010,714 (the “714 patent”), which is hereby incorporated by reference herein, it is known to add a heat dissipating agent to a cyanoacrylate adhesive in order to reduce the amount of heat generated upon polymerization of the monomer. The '714 patent discloses adding heat dissipating agents such as ethers, ketones, chlorofluorocarbons, alkanes, alchohols, alkenes and mixtures thereof. The heat dissipating agents disclosed in the '714 patent are useful for adhesive compositions having relatively low viscosities, e.g. 40-50 cp. There remains a need for a relatively thicker surgical adhesive that does not cause thermal damage or necrosis of living tissue after application of the adhesive to the tissue. Therefore, there is a need for an additive or a combination of additives that will reduce the amount of heat released or exotherm generated during the polymerization of a cyanoacrylate monomer.